This project is designed to encourage communication and cooperation among the institutions in the investigation of the role of intra-abdominal malignancies. The project is also designed to encourage cooperation in a coordinated program toevaluate the use of radiation modifiers in conjunction with intraoperative radiotherapy. The ultimate goal is to develop guidelines for Phase II and randomized, Phase III studies to evaluate intraoperative radiotherapy, alone or withradiation modifiers, for the treatment of intra-abdominal malignancies initially and, later, in other sites.